Topic Contents

Follicle-Stimulating Hormone

Test Overview

A follicle-stimulating hormone test measures
the amount of follicle-stimulating
hormone (FSH) in a blood sample. FSH is produced by
the
pituitary gland.

In women, FSH helps control the
menstrual cycle and the production of eggs by the
ovaries. The amount of FSH varies throughout a woman's
menstrual cycle and is highest just before she releases an egg
(ovulates).

In men, FSH helps control the production of sperm. The
amount of FSH in men normally remains constant.

The amounts of FSH and other hormones (luteinizing hormone,
estrogen, and progesterone) are measured in both a man and a woman to determine
why the couple cannot become pregnant (infertility).
The FSH level can help determine whether male or female sex organs (testicles or ovaries) are functioning properly.

Why It Is Done

A follicle-stimulating hormone (FSH)
test may be done to:

Help find the cause of infertility. FSH testing
is commonly used to help evaluate a:

Woman's egg supply (ovarian
reserve).

Man's low sperm count.

Help evaluate menstrual problems, such as
irregular or absent menstrual periods (amenorrhea). This can help determine
whether the woman has gone through
menopause.

Determine if a child is going
through early
puberty (also called precocious puberty). Puberty is
early when it starts in girls younger than age 9 and in boys younger than age
10.

Determine why sexual features or organs are not developing when
they should (delayed puberty).

Help diagnose certain pituitary
gland disorders, such as a tumor.

How To Prepare

Many medicines, such as cimetidine,
clomiphene, digitalis, and levodopa, can change your test results. You may be
asked to stop taking medicines (including birth control pills) that contain
estrogen or progesterone or both for up to 4 weeks
before having a follicle-stimulating hormone (FSH) test. Make sure your doctor
has a complete list of all the prescription and over-the-counter medicines you
are taking, including herbs and natural substances.

Tell your
doctor if you have had a test that used a radioactive substance (tracer) within
the last 7 days. Recent tests using a radioactive tracer (such as a thyroid
scan or bone scan) can interfere with FSH test results.

Let your
doctor know the first day of your last menstrual period. If your bleeding
pattern is light or begins with spotting, the first day is the day of heaviest
bleeding.

Talk to your doctor about any concerns you have
regarding the need for the test, its risks, how it will be done, or what the
results will mean. To help you understand the importance of this test, fill out
the
medical test information form(What is a PDF document?)
.

How It Is Done

The health professional drawing your
blood will:

Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.

Clean the needle site with
alcohol.

Put the needle into the vein. More than one needle stick
may be needed.

Attach a tube to the needle to fill it with
blood.

Remove the band from your arm when enough blood is
collected.

Apply a gauze pad or cotton ball over the needle site as
the needle is removed.

Apply pressure to the site and then a
bandage.

For a woman who is having problems with her menstrual cycle
or who cannot become pregnant, more than one blood sample may be needed to help
identify a follicle-stimulating hormone (FSH) problem. A sample may be taken
each day for several days in a row.

How It Feels

You may feel nothing at all from the
needle puncture, or you may feel a brief sting or pinch as the needle goes
through the skin. Some people feel a stinging pain while the needle is in the
vein. But many people do not feel any pain or have only minor discomfort once
the needle is positioned in the vein.

Risks

There is very little risk of complications from
having blood drawn from a vein.

You may develop a small bruise at the puncture
site. You can reduce the risk of bruising by keeping pressure on the site for
several minutes after the needle is withdrawn.

In rare cases, the
vein may become inflamed after the blood sample is taken. This condition is
called phlebitis and is usually treated with a warm compress applied several
times daily.

Continued bleeding can be a problem for people with
bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning
medicines can also make bleeding more likely. If you have bleeding or clotting
problems, or if you take blood-thinning medicine, tell your doctor before your
blood is drawn.

Results

A follicle-stimulating hormone test
measures the amount of follicle-stimulating
hormone (FSH) in a blood sample. The test results
depend on your age and stage of sexual development.

The phase of a
woman's
menstrual cycle can affect results, so it is important
to know the first day of your last menstrual period at the time the test is
performed.

Low values

A tumor is present that interferes with the brain's ability to
control FSH production.

Stress.

Starvation or being
very underweight.

What Affects the Test

Results of the
follicle-stimulating hormone (FSH) test may be affected by:

The use of hormones, such as testosterone,
estrogen, and progesterone (including birth control pills).

Heavy
cigarette smoking.

Age.

The use of medicines, such as
cimetidine, clomiphene, digitalis, and levodopa. Make sure your doctor has a
complete list of all the prescription and over-the-counter medicines you are
taking, including herbs and natural substances.

Having a test such
as a thyroid scan or bone scan that uses a radioactive substance within 1 week
of the FSH test.

What To Think About

If you are taking a medicine that contains
testosterone, estrogen, or progesterone (such as birth control pills), ask your
doctor whether you should stop taking it for several days before having a
follicle-stimulating hormone (FSH) test.

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